At present, only single genes, or very small groups of genes, can be transferred. Example of such characteristic are resistance to disease and to herbicide, such as glyphosate. Fields can be sprayed with the herbicide,but only the weed species die since the genetically engineered crop plant are resistant to it. The farmer have to spary fewer times as glyphosate is more effective than other weedkillers. This is less damaging to the environment.